The synthesis of cholest-5-ene-3 beta-carboxylates and a comparison of their mesomorphic behaviour with isomeric cholesterol esters with a reversed ester linkage

The syntheses of seven esters of cholest-5-ene-3 beta-carboxylic acid are r eported and the melting points, transition temperatures and mesophase morph ologies of the esters are compared with those of the isomeric 3 beta-choles terol compounds which have the ester link reversed. For the examples report ed, the cholest-5-ene-3 beta-carboxlates always have significantly lower me lting points, but the differences in clearing temperatures for the two seri es of esters are usually much less. Several of the new compounds give an in creased chiral nematic phase range and an intense selective reflection of l ight. They therefore represent a novel type of chiral nematic material for use in thermochromic applications.